On the Penetration of Oil into Paper (Part 2)

Abstract

Contact angle was discussed, relation on P versus, √t on three species of the sanAple were plotted for five kind of oil, and the first slope (F. S.) and the second slope (S. S.) were determined.If ?A=O i. e. cos θ=1, the ratio of F.S. and S.S. between two kinds of oil in the same paper (Y axis), should have a straight line to the ratio √surface tention/viscosity coeffcient of each oil (X axis), and the line should pass the original point, its slope should be 1.The regression line on 70 point of the experimental value, clossed the Y axis at -0.101 and its slope was 1.106, and we have tested statistically that this line was not different significantly to the theoretical line.From the fact mentioned above and the fact that in some cases the slope on S.S.is greater than that on F.S., it is likely that the contact angle is a little larger than zero.Assuming that the mean hydraulic radius which was calculated from the data on the oil penetration method by applying Kozeny-Carman equation is equal to the average paper capillary radius, we can calculate number of capillary per unit area and the product of mean hydraulic radius and number of capillary. Hydraulic radius was measured with the constant pressure air permeability apparatus and number of capillary was calculated from these radii. But the physical meaning of number of capillary are not clearly understood.On the discussion from the various consideration, it might be concluded that paper should have a different layer on vertical direction. On the paper that the slope of F. S. is greater than that of S.S. penetrating velocity have to be determined on the second layer and so, relation between the number of capillary product with mean hydraulic radius and hydraulic radius by permeability method, should have good correlation value. Actually we have the correlation coefficient almost nearly. The correlation coefficient on the first layer should be lower than that on second layer, and actually it was 0.35.